Systems for direct injection of fuel into the combustion chamber of an internal combustion engine are known in general. A distinction is made between homogeneous operation as the first operating mode and stratified charge operation as the second operating mode. Stratified charge operation is used in particular at low loads applied to the internal combustion engine, while homogeneous operation is used at higher loads. In stratified charge operation, fuel is injected into the combustion chamber during the compression phase of the combustion engine, specifically, it is injected into the immediate vicinity of a spark plug. Consequently, there no longer is a uniform distribution of fuel in the combustion chamber, but instead the fuel is immediately ignited by the spark plug. The advantage of stratified charge operation is that smaller loads can be handled by the engine with a much smaller fuel mass. However, higher loads cannot be handled by stratified charge operation. In the homogeneous operating mode provided for such higher loads, fuel is injected during the intake phase of the combustion engine, so that turbulence can be created in the fuel to ensure a good distribution of fuel in the combustion chamber. To this extent, homogeneous operation corresponds approximately to the operating mode of internal combustion engines wherein fuel is injected into an intake manifold leading to the combustion chamber in the traditional manner.
In both operating modes, i.e. in stratified charge operation and in homogeneous operation, the amount of fuel injected is controlled and/or regulated as a function of multiple input parameters to optimize fuel savings, reduce exhaust, etc. The control and/or regulation is different in the two operating modes.